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Three searches are presented for signatures of physics beyond the standard model (SM) in $ττ$ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at $\\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb-1. Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into $τ$ leptons and the cross sections for the production of a new boson $\\phi$, in addition to the H(125) boson, via gluon fusion (gg$\\phi$) or in association with b quarks, ranging from $\\mathcal{O}$(10 pb) for a mass of 60 GeV to 0.3 fb for a mass of 3.5 TeV each. The data reveal two excesses for gg$\\phi$ production with local $p$-values equivalent to about three standard deviations at m$\\phi$ = 0.1 and 1.2 TeV. In a search for $t$-channel exchange of a vector leptoquark U1, 95% CL upper limits are set on the dimensionless U1 leptoquark coupling to quarks and $τ$ leptons ranging from 1 for a mass of 1 TeV to 6 for a mass of 5 TeV, depending on the scenario. In the interpretations of the $M^{125}_{h}$ and $M^{125}_{h,EFT}$ minimal supersymmetric SM benchmark scenarios, additional Higgs bosons with masses below 350 GeV are excluded at 95% CL.

Abstract The production of prompt Λ c +$$ {\\Lambda}_{\\textrm{c}}^{+} $$baryons is measured via the exclusive decay channel Λ c + → p K − π +$$ {\\Lambda}_{\\textrm{c}}^{+}\\to p{\\textrm{K}}^{-}{\\pi}^{+} $$at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb −1, respectively. The measurements are performed within the Λ c +$$ {\\Lambda}_{\\textrm{c}}^{+} $$rapidity interval |y| < 1 with transverse momentum (p T) ranges of 3–30 and 6–40 GeV/c for pp and PbPb collisions, respectively. Compared to the yields in pp collisions scaled by the expected number of nucleon-nucleon interactions, the observed yields of Λ c +$$ {\\Lambda}_{\\textrm{c}}^{+} $$with p T > 10 GeV/c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The Λ c +$$ {\\Lambda}_{\\textrm{c}}^{+} $$/D0 production ratio is similar in PbPb and pp collisions at p T > 10 GeV/c, suggesting that the coalescence process does not play a dominant role in prompt Λ c +$$ {\\Lambda}_{\\textrm{c}}^{+} $$baryon production at higher p T.

Abstract A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at$${\\sqrt{s}=13\\,\\text {Te}\\hspace{-.08em}\\text {V}}$$s = 13 Te V by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138$$\\,\\text {fb}^{-1}$$fb - 1 . The 95% confidence level upper limit set on the branching fraction of the 125$$\\,\\text {Ge}\\hspace{-.08em}\\text {V}$$Ge V Higgs boson to invisible particles,$${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$B ( H → inv ) , is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous$${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$B ( H → inv ) searches carried out at$${\\sqrt{s}=7}$$s = 7 , 8, and 13$$\\,\\text {Te}\\hspace{-.08em}\\text {V}$$Te V in complementary production modes. The combined upper limit at 95% confidence level on$${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$B ( H → inv ) is 0.15 (0.08 expected).

Abstract The second-order (v 2) and third-order (v 3) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of s NN$$ \\sqrt{s_{\\textrm{NN}}} $$= 5.02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb −1 recorded with the CMS detector. The J/ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. The v 2 and v 3 coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured v 2 values for prompt J/ψ mesons are found to be larger than those for nonprompt J/ψ mesons. The prompt J/ψ v 2 values at high p T are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/ψ meson v 3 and prompt ψ(2S) v 2 and v 3 values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions.

Abstract The mass of the top quark is measured in 36.3$$\\,\\text {fb}^{-1}$$fb - 1 of LHC proton–proton collision data collected with the CMS detector at$$\\sqrt{s}=13\\,\\text {Te}\\hspace{-.08em}\\text {V} $$s = 13 Te V . The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables per event to extract the top quark mass. The top quark mass is measured to be$$171.77\\pm 0.37\\,\\text {Ge}\\hspace{-.08em}\\text {V} $$171.77 ± 0.37 Ge V . This approach significantly improves the precision over previous measurements.

Abstract A search for the electroweak production of a vector-like quark T′, decaying to a top quark and a Higgs boson is presented. The search is based on a sample of proton-proton collision events recorded at the LHC at s √s̅ = 13 TeV, corresponding to an integrated luminosity of 138 fb −1. This is the first T′ search that exploits the Higgs boson decay to a pair of photons. For narrow isospin singlet T′ states with masses up to 1.1 TeV, the excellent diphoton invariant mass resolution of 1–2% results in an increased sensitivity compared to previous searches based on the same production mechanism. The electroweak production of a T′ quark with mass up to 960 GeV is excluded at 95% confidence level, assuming a coupling strength κ T = 0.25 and a relative decay width Γ/M T′ < 5%.

Abstract The double differential cross sections of the Drell–Yan lepton pair ($$\\ell ^+\\ell ^-$$ℓ + ℓ - , dielectron or dimuon) production are measured as functions of the invariant mass$$m_{\\ell \\ell }$$m ℓ ℓ , transverse momentum$$p_{\\textrm{T}} (\\ell \\ell )$$p T ( ℓ ℓ ) , and$$\\varphi ^{*}_{\\eta }$$φ η ∗ . The$$\\varphi ^{*}_{\\eta }$$φ η ∗ observable, derived from angular measurements of the leptons and highly correlated with$$p_{\\textrm{T}} (\\ell \\ell )$$p T ( ℓ ℓ ) , is used to probe the low-$$p_{\\textrm{T}} (\\ell \\ell )$$p T ( ℓ ℓ ) region in a complementary way. Dilepton masses up to 1$$\\,\\text {Te\\hspace{-.08em}V}$$Te V are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various$$m_{\\ell \\ell }$$m ℓ ℓ ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3$$\\,\\text {fb}^{-1}$$fb - 1 of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13$$\\,\\text {Te\\hspace{-.08em}V}$$Te V . Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.

Abstract A search for long-lived particles decaying in the outer regions of the CMS silicon tracker or in the calorimeters is presented. The search is based on a data sample of proton-proton collisions at s √s̅ = 13 TeV recorded with the CMS detector at the LHC in 2016–2018, corresponding to an integrated luminosity of 138 fb −1. A novel technique, using nearly trackless and out-of-time jet information combined in a deep neural network discriminator, is employed to identify decays of long-lived particles. The results are interpreted in a simplified model of chargino-neutralino production, where the neutralino is the next-to-lightest supersymmetric particle, is long-lived, and decays to a gravitino and either a Higgs or Z boson. This search is most sensitive to neutralino proper decay lengths of approximately 0.5 m, for which masses up to 1.18 TeV are excluded at 95% confidence level. The current search is the best result to date in the mass range from the kinematic limit imposed by the Higgs boson mass up to 1.8 TeV.

Abstract A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production ($$\\hbox {t}\\overline{\\hbox {t}}$$t t ¯ ) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400$$\\,\\text {Ge}\\hspace{-.08em}\\text {V}$$Ge V . The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138$$\\,\\text {fb}^{-1}$$fb - 1 . The differential$$\\hbox {t}\\overline{\\hbox {t}}$$t t ¯ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of$$173.06 \\pm 0.84\\,\\text {Ge}\\hspace{-.08em}\\text {V} $$173.06 ± 0.84 Ge V .